Hongfu FM079

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by Klaster_1


Update 09.05.2019: the live and up to date build list is here, complete (almost) with scale shots.

The old first post:

First time (well, almost) poster here, took awhile before I've gathered enough courage to post one of my bikes here. It'a Hongfu FM-079, the build was started in 2014. Back then I didn't have any prior experience with road bikes and wanted something more suitable for pavement than an 26" XC hardtail. During June 2014 - March 2015 I've picked, bought and built everything together. Initially, the budget was about 2500USD+ with the following requirements:
  1. Road specific carbon fiber disc frame. After some search, I've picked FM79. Not like there were much other options.
  2. Shimano 11 speed hydraulic groupset. I wanted something modern and didn't might to become an early adopter. Compatibility with tools and MTB parts already owned played a big role too. Hydraulic shifter options were limited at the day to RS-785 and ST-RS685. Since ST-RS505 wasn't out yet and DI2 was out of budget, 785 became an only option with 5800 filling the rest.
  3. Tubeless compatible clinchers, but not XC-tier shallow. Light-Bicycle laced to Novatec 711/712 proved to be a good choice, albeit on a heavy side.
Due to points above and general lack of experience, the first version of build came to be about 8.1kg. Summer 2015 helped me to understand where to and how the bike might progress towards. I also got more disposable income to spend.

During 2016, I've progressively swapped most of easy gain parts to their lightweight counterparts.

Build list as of today:

Code: Select all

Component Type               Component               Weight (Grams)      Note
Frame                        Hongfu FM-079           1040                Claimed weight, 56cm
Fork                         Hongfu HF-FK166         415                 Steerer cut, with crown race; 22.3mm internal diameter
Fork hose clamp              Hongfu                  3                   Two Phillips screws and U-clamp
Headset bearings             Neco                    50                  educated guess
Headset cap                  Neco                    11                  5mm
Steerer spacer               Hongfu                  5                   1cm
Top cap                      MT ZOOM                 3                   Works with sunken expander only
Top cap bolt                 MT ZOOM                 2                  
Bars                         Hylix Ergonova          186                 44cm, uncut
Stem                         Kalloy Uno 7            94                  11cm, paint stripped
Stem bolts                   J&L                     12                  ti, black
Expander plug                J&L                     12                  Tuned, new brass bottom with longer shaft (+5g)
Bar tape                     Velo Gel Wrap           64                  cut
Seatpost (bare)              Hongfu                  105                 Cut off 80mm and 23g; 141 total
Seatpost cradle              Hongfu                  15                 
Seatpost bolt                                        3                   ti
Seatpost bolt                                        4                   ti
Seatpost yokes               J&L                     14                  M5, 7075
Seatpost clamp               MT ZOOM                 10                  34.9mm shimmed down to 32.3mm
Saddle                       Saevid Alien            78                 
Bar end plugs                SRAM                    4                   educated guess
Crankarms                    Zipp Vumaquad           442                 172.5; with rings; decals sanded down
Chainring big                Fibre-Lyte                                  50
Chainring small              Fibre-Lyte                                  34
Chainring bolts              Zipp                                       
Bottom bracket               Zipp                    72                  ceramic bearings
Front derailleur              Shimano FD-9000         65                  stock
Rear derailleur               Shimano RD-9000         161                 stock
Shifters                     Shimano ST-RS785        648                
Cassette+lockring            Shimano CS-5800         277                 11-28
Chain                        Shimano HG600           246                 cut down from 266
Pedals                       Xpedo R-Force Ti        166                
Brake calipers               Shimano BR-RS685        218                 109 per set
Brake pads+spring                                    42                  21 per set
Brake olives+barbs                                   14                  7 per set
Shifting cables                                      38                  uncut
Hydraulic hoses              Shimano                 52                  2700mm
Rims                         Light-Bicycle           870                 35mm U hookless, 2 total
Front hub                    Novatec D711SB          139                 408
Rear hub                     Novatec D712SB          269                
Skewers                      J&L                     30                  Bolt on
Spokes+nipples               Pillar PSR X-TRA1420    280                 56 total; 4 spares weight 20g
Front tire                   Schwalbe One Tubeless   370                 25mm, used & with sealant stuck
Rear tire                    Schwalbe Pro One        240                 25mm, new
Tire sealant                 Stan's NoTubes          50                  40ml per wheel
Bottle cage                  TUNE Wasserträger 2.0   9                   750ml bottle
Bottle cage bolts            TUNE Wasserträger 2.0   2                  
Rim tape                     Stan's Yellow Tape      12                  6 per wheel
Valve stems                  Gredes                  20                  60mm, 10 per set
Front rotor                  KCNC Razor              61                  140mm
Rear rotor                   KCNC Razor              62                  140mm
Rotor bolts                  J&L                     15                  ti
Computer sensor              Cateye Strada Slim      13                 
Computer head unit+clamp     Cateye Strada Slim      16                 
Caliper bolts                J&L                     12                  ti
                           Total                     7041               
Unfortunately, I didn't weight the frame, headset and housings, so those are listed with claimed values or a rough estimate. To my surprise, scales show exactly 7.00kg, a respectable disc bike weight in my book.

Since the winter is at door, the bike's going to serve as wall decoration until April. I plan to drop the weight down to about 6.8kg mark with these:
  1. Schwalbe Pro One in the front, about 70g less than One Tubeless. Already own it.
  2. XG-1190, still not sure if 11-26 or 11-28, -100-110g.
  3. PC Red-22 chain, -10-15g.
  4. Minor derailleurs tuning. J&L inner cage, carbon pulleys, nylon limit bolts and FD clamp bolt will save about 10g.
  5. Bar tape, current one is way too porky, but it was the only thing I could source locally fast. I'd be glad to drop 10g here.
Obviously, there are more substantial gains, but prices skyrocket fast.
  1. Frameset. 250g+ saving can't be made with open mold products of today. Big brands will cost at least 1500USD. New frame also requires thru axle hubs and flat mount calipers.
  2. ST-R9120 shifters are 150g lighter, but cost about 1000EUR at the moment. Not an option unless price drops at least twice, which isn't going to happen until used units become readily available in several years. Works only with FD-9100 too, so add a new derailleur cost.
  3. Wheels. Tons of options here. I'd replace Novatecs with Cyber hubs SPD-2 for ~200g saving, but those are not available in 28 holes. All open mold rims weight about the same and I'm not going shallower. 77 Composites go for 1000EUR apiece, way out of budget. And as a casual rider I'm very hesitant of tubulars. Potentially, there's about 500g to save with top of the line clinchers for 2800EUR.
  4. Seat/seatpost combo. At least 100g to lose here for a reasonable 400EUR. Still, I will have to be 100% sure about fitting, which I'm not.
  5. Marginal 10-30g savings everywhere for hundreds of EUR. Worth a shot if it's the cheapest option to reach 6.8kg.
All in all, I think 6.0kg is possible, but would cost 4000EUR or more and I'm not willing to go down that road.

Oh, and I don't race or go for really long rides, but riding experience has been great so far. There were some annoying moments, though:
  1. FM079 has clearance issue with FD-9000 design. The smaller small chainring becomes, the more evident it is. Making 34 shift acceptably was harder than 36, but then again, I don't do that often. Other people already wrote about this several times.
  2. Overbuilt fork. The steerer tube has quite small internal diameter, I had to heavily modify J&L UltraStar 2 clone so it would fit in.
  3. Seat tube diameters are off. I suspect that inner diameter is less than it should have been, since stock seatpost measures 27.0mm and fits just great. Outside diameter is 32.3mm, which limits clamp design. Stock clamp with rotating nut works fine, but is way heavy at 25g. MTZOOM 31.8 collar, on the other hand, didn't allow to screw the bolt in due to messed up angle. I had to use 34.9 collar and a shim.
  4. Frontmost seatpost yokes had to be cut at angle a bit due to interference with Saevid Alien bottom edge.
  5. New frame had defects missed by quality control. One of the post mount holes wasn't completely threaded, so I had to ask friend with tools to help. The other issue was with one of bolt holes in seatpost head, I had to sand a drop of resin inside one bolt hole in order to put it in.
Looking back, I'd advice against purchase of post mount version of FM079. There are products that offer both lesser weight, flat caliper mounts, 12mm through axle support and no front derailleur clearance issues.

Hongfu FM079 build list (06.07.2019).png
Hongfu FM079 build list (06.07.2019)
Klaster_1's Hongfu FM079 (23.06.2019)
Last edited by Klaster_1 on Sat Jul 06, 2019 10:38 am, edited 15 times in total.

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by Kayrehn

That's a very respectable first post! Love your research even though you know you don't want to go that far out. Ride the shit out of it and have fun

by Weenie

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by Tomstr

Very nice! 1558grams is nice work too, could you tell a bit more about the internal width of the rims and how the wheels hold up?
Ride it like you stole it

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by tarmackev

Yes that's a great first post.
You seem to have educated yourself well.
I'm sure we'll see some amazing stuff from you in the future.

Sent from my iPhone using Tapatalk

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by Klaster_1

Tomstr wrote:Very nice! 1558grams is nice work too, could you tell a bit more about the internal width of the rims and how the wheels hold up?

Here's the LB page with specs. I'm not sure if there's any difference between regular and hookless versions. Outer width measures 25mm, 25mm tires are ~28mm wide when mounted. I didn't experience any issues with wheels so far. Tubeless setup was a breeze, albeit somewhat tight bead clearance.

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by Klaster_1

So I've been thinking about reasonable ways to drops some weight from shifters, I see two options without going SRAM. One is easy, but only drops 140 grams:

Code: Select all

Component               Weight  Price
ST-R9120                505     554 EUR
FD-R9100                69      90 EUR

                        574     644

Difference to current (650 + 65 = 715)


The other one is full of unknowns, I have no idea how good Xshifter will be, how much levers actually weight / cost and if there are compatible disc calipers at all. In addition I lose drop bars and a lot of cash.

Code: Select all

Component               Weight  Price
Xshifter Dual           110     339 USD
Xremote Road            30
Hylix bullhorn          165     73 USD
Magura RT-8 TT levers   ~200    ~763 with calipers


                        505     1175

Difference to current (185 + 650 = 835)


Spreadsheets are surprisingly fun, even if I most likely won't proceed with something crazy like that.

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by PaulG

XShifter will likely be your lightest option. It seems counter-intuitive that a servo and battery is lighter than mechanical, but it is.

Our single servo is 80 gram. The dual is 110. (Including battery). Cable length is very short so not a big factor. The remote control is roughly 30g And we are working on ideas to make them lighter yet.

Where you can save even more weight, is in the derailleurs and hoods. XShifter works with anything, so you can buy the lightest weight derailleurs that are still good, and you get the benefit of electronic shifting. You can get some very lightweight brake hoods, and still have electronic shifting.

For comparison, the SRAM eTap RD is about 80gram heavier than their standard derailleur, which isn't so light to start with.

We are working on some options that will allow any OEM to package our remote control in their hoods, which should get very interesting.

I'm very familiar with how to save weight on bike parts. When I developed SRAM's Guide Ultimate and Level calipers that was one of the biggest factors. I was able to make it lighter, and still outperform the heavier, older product. It takes a lot of work and optimization to do this.

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by Klaster_1

The bike is officially under 6.8 kg now. You can't see that on picture, but I've replaced bar tape, cassette and front tire since last post. Complete build list is here. No idea where to proceed further, I think I'll get new valve stems, headset bearings and stem for about 55g saving and maybe ST-R9120 levers, which should make another ~150 gramms. Then comes the hard part: do I build 1kg shallow tubulars, will non-setback seatpost work, maybe a combo? Christoph Hopp also mentioned that they might have road rear derailleur CF tuning parts too, but at prohibitive price.

And a photo from last ride:

Tomstr wrote:could you tell a bit more about the internal width of the rims

Finally was able to measure it today, internal width is 20mm. Bear in mind that rims are hookless.

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by Klaster_1

Did not post here in a long time. My thread only has a single page anyway 😁. In fact, I have multiple upgrade spreadsheets spanning 1-2 years in the future, limited by parts availability and spare cash. I think it's safe to reveal latest updates: Berk Lupina saddle, Darimo T1 seatpost, Workswell WCB-R-093 fork (flat mount, 330g uncut), Hope RX4 Shimano calipers and a bunch of small stuff, like PYC chain, FSA headset bearings, Tune valves and Jagwire XEX-SL housing. The calculations predict 220-250g weight loss, which should be enough to hit the 6.5kg mark.
Extralite 12mm TA weight.
Rear RX4 weight.
Front RX4 weight.
Workswell WCB-R-093 fork.
New front wheel assembly.
Seatpost/saddle combined weight.
New seatpost and saddle mockup on the bike.

One interesting thing to note is the front hub conversion I did. The old Novatec D711SB front hub supports 9mm QR, but after some research I found out that the axle has almost 12mm inner diameter (~11.8mm). After asking around, I got into contact with a machinist who bored the axle to 12mm and manufactured custom 12mm TA endcaps I designed in FreeCAD. Learning how to use a CAD software was quite straightforward, I was amazed by how easy you can get first results from it. The whole machining part cost me an equivalent of 12USD.
Endcap CAD screenshot.
Custom Novatec D711SB 12mm thru axle endcaps.

I hope everything goes fine, but I'm still worried about caliper/fork compatibility and the soundness of DIY hub conversion.

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by Klaster_1

Today I've installed the front RX4-SH caliper. The barb was impossibly tight to fit into BH-90 hose barehanded, I was able to put only a millimeter in. Resin gloves helped with traction, but for final 2mm I had to warm the hose a bit with a hair dryer. Another tight place and one of my concerns was caliper/fork clearance and hose angle. Apparently, it does fit, with about a millimeter between hose shroud and fork leg. The hose bends a fair bit, but nothing too excessive in my opinion, I did not even have to warm it up. Fully integrated TT disc frames probably have it worse.
Shroud/fork clearance.
The hose.

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by kidrob

Yes, very very nice! Great upgrades, keep them coming :)

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by Klaster_1

Because I did not weight the frame after purchase, I decided to disassemble the bike completely in order to fill the gaps in my build spreadsheet. Still not done yet, but here's a useful photo of BR-RS785 on scales, I failed to find one like this before. Maybe soon the "BR-RS785 weight" query will yield my thread as the first result 8) The bare RX4-SH post mount caliper is a good 25g lighter than BR-RS785. Tomorrow I'll try to weight the mounting hardware of both calipers and pad pins.
Current disassembly progress.
BR-RS785 weight

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by Klaster_1

Nice, the frame weights 982g, 60g less than my estimation and about 80g more than a 49cm from this thread. That includes FD/RD hangers and Shimano FD spacer plate. The headset cups and BB shell are bonded aluminium, there's a decent amount to save with BB30 and CF cups, I wonder if FM079F received these upgrades.
Hongfu FM079 56cm weight

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by Klaster_1

Bad news, the fork sits a tad too deep inside the head tube: with slack bearing preload it rotates freely, but after a bit of preload the fork crown rubs the cup slightly. All of this happens with a tall Neco lower bearing. The FSA ACB bearing I was planning to use has a stack lower by about 2mm, as things are now I won't be able to use it at all.
WCB-R-093 fork installed into Hongfu FM079 frame.
I see at least two ways to solve the issue:
1. File down the bottom headset cup a bit. I'd rather not, also heavy bearing.
2. Make a bearing spacer. This way I can use FSA ACB too. The spacer should be ~3.2g if made from aluminium.

Any ideas about the spacer, did anyone try that, maybe there are similar products available?
headset bearing spacer.png
Lower headset bearing spacer.

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by gilles75

Hi Klaster,
I am curious about your saddle choice. Did you replace the Saevid Alien by the Lupina for weight reduction only, or for comfort reasons? Do you see a noticeable shape difference when seating? How do you compare these two saddles?
I am very comfortable on Spesh Toupe and Smud Carbon saddles, and recently installed an Alien on my S3. I did not spend a lot of time on it yet. I chose it because it looks similar to a Toupe, but my impression when seating is that it will feel narrower. Time will tell if I can keep it...

by Weenie

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